Thixotropic cleaning agent for hard contact lenses

ABSTRACT

A thixotropic gel cleaner is provided for hard contact lenses. The cleaning agent is ordinarily packaged in a tube which makes it easy to carry without danger of leakage and it is convenient and effective to use.

United States Patent [191 Phares, Jr. et al.

[451 May 20, 1975 THIXOTROPIC CLEANING AGENT FOR HARD CONTACT LENSES [75] inventors: Russell E. Phares, Jr., San Jose;

Rebecca F. Nite, Sunnyvale, both of Calif.

[73] Assignee: Barnes-Hind Pharmaceuticals, Inc., Sunnyvale, Calif.

22 Filed: July 20,1973

21 App]. No.: 381,179

[52] U.S. Cl. 252/106; 252/89; 252/352; 252/D1G. 1; 252/D1G. 2; 424/78; 424/81 [51] Int. Cl ..C1ld 3/48 [58] Field of Search 252/106, 352, 89, DIG. 2, 252/DIG. 1; 424/78, 81

[56] References Cited UNITED STATES PATENTS 7/1967 Hernandez 252/90 OTHER PUBLICATIONS Carbopol 934, Servicepp. pgs. 1,20, 21 and 25 (l960), B. F. Goodrich Chemical Company.

Primary ExaminerBenjamin R. Padgett- Assistant ExaminerE. A. Miller [57] ABSTRACT A thixotropic gel cleaner is provided for hard contact lenses. The cleaning agent is ordinarily packaged in a tube which makes it easy to carry without danger of leakage and it is convenient and effective to use.

8 Claims, N0 Drawings THIXOTROPIC CLEANING AGENT FOR HARD CONTACT LENSES SUMMARY OF THE INVENTION The necessity of cleaning hard contact lenses has been long recognized, and many agents and mechanical devices have been proposed for this purpose.

Contact lens residue can very well come from the healthy eye secretions. Tear fluid has 1.8% total solids consisting of sugars, lipids, salts, mucopolysaccharides, organic acids, enzymes and proteins. Although most of these are water soluble, others are not and are dispersed as colloids and others, such as meibomian oil,

are not at all water soluble. Many of these substances tenaciously adhere to a lens and require a cleaner to be removed. Mucus overproduction that is caused by improperly fitted lenses, infection and irritation due to ailergens in the environment, also contribute to the deposit on the lens.

The patients own fingers are a major source of contact lens soil. While handling the lens, a patient may be transferring perspiration, sebum, nicotine, hand lotions, mascara and other cosmetics from his hands to his lenses.

Even the air is a source of soil. Smog, smoke, and various sprays with all their differently charged particles can easily deposit on the lens surface.

Since it is not easy to avoid getting this residue, cleaning of lenses to prevent this build-up and the possible danger and discomfort due to it should be religiously practised.

Among the materials and methods that have been employed, the following may be mentioned:

1. Strong alkaline or corrosive chemicals that may prove irritating to patients if not completely removed, or that may attack lens material and reduce clarity.

2. Mechanical cleaning, perhaps with the aid of a hard bristle toothbrush and an abrasive tooth powder. Since these abrasives scratch the soft plastic surface of the lens, they are always contraindicated.

3. Solvents, such as lighter and dry cleaning fluids. Many of the low boiling point solvent components of lighter fluid and cleaning compositions do clean. Unfortunately, they contain residual amounts of higher boiling point petroleum derivatives that stay on the lens surface. The result is an even more devastating form of foreign matter.

Such agents have not been uniformly successful in the past, and if the lenses are not properly cleaned, a residue will be left on the lens, resulting in irritation to the wearer and, in extreme cases, poor vision. In addition, this build up of the residue may inhibit wetting activity and trapped bacteria, thus preventing any soaking solution which might be used from exerting antibacterial effects.

There are many products, other than cleaners, that contact lens wearers might be using such as a wetting solution, sterilizing and hydrating solution, artificial tear, decongestant or cushioning preparation. Some of these products are intended for use in the eye but others should be used only outside the eye. Cleaners for contact lenses are generally designed for use outside the eye but recently a cleaner that works in the eye has been marketed. A contact lens cleaner that is to be used outside the eye can easily be confused with a solution designed for use in the eye, especially if the cleaner is also asolution and the patient is not wearing his lenses.

In accordance with the present invention, a cleaner is provided in the form of a thixotropic gel. Although cleaners in gel form have been proposed in the past, they have not been thixotropic and, ordinarily in use, they are too thick to be effective since it is well established that a minimum viscosity enhances cleaning ability. The gel of the present invention combines the advantages of a semi-solid material with those of a liquid material.

Since the material is in the form of a gel, it can ordinarily be packaged in a tube, which makes it much eas-- ier to carry in a purse or pocket and there is little danger of leaking, even if the tube is stored on its side or upside down.

In gel form, it is easy for a user to squeeze out just the right amount of cleansing agent without wasteful and messy dripping.

A further advantage of the gel is that there is no mistaking the cleaning agent for other agents which are normally used with hard contact lenses, such as wetting or soaking solutions. Since many users of contact lenses have poor visual accuity, there is no mistaking the cleaning agent for other agents which are used in the form of liquids even if the user has neglected to read the label on the container.

A further advantage of the thixotropic gel is that it gives the patient something substantial to work on and he can feel the cleaner in contact with thesurface of his lens and will ordinarily do a' more thorough cleaning of the lens than with a liquid. I

The thixotropic gelof the pres'entinvention is a very effective cleaner for contact lenses. It has been tested and found effective for a number of soilants on hard contact lenses such as mascara, oils, marker pen and most hair sprays. It is even effective for removing lipstick, hand cream and black china marker.

Not only does the cleaner of the present invention provide effective cleaning of the lens surface, but it promotes better wetting when the lens is subsequently stored in a wetting solution or wetted with wetting solution prior to insertionin the eye. Even if the cleaner is rinsed off the lens after cleaning, enough of the cleaner is retained on the lens to render the surface more easily wetted by wetting agents than lenses that have been cleaned only with water or conventional cleaning solutrons.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the simplest form, the formulation of the present invention merely consists of a thixotropic solution of a gelling agent, together with a small amount of cleansing agent. The gelling agent is used in sufficient amount to render the cleaner thixotropic and to give a suitable viscosity. A suitable viscosity range has been found to be 15,000 to 70,000 cps and it is preferred that the viscosity be about 30,000 to 50,000 cps (Brookfield RVF microviscometer spindle 6 at 20 RPM at 25C). If the product is too fluid, it will usually run off the finger before rubbing and would be wasteful, since it would be difficult for the patient to regulate the amount being dispensed from the container. On the other hand, too stiff a gel is not easily spread on the lens surface and might be tacky and not easily rinsed off. Since the gel of the present invention is thixotropic, a stiffer gel may be employed than for gel cleaners which have been proposed in the past which are not thixotropic.

Various gelling agents may be employed such as high molecular weight'carboxyvinyl polymers sold under the trade name Carbopol by B. F. Goodrich Company. Concentrations of from 0.1 to 5% yield a suitable viscosity as defined above. Other typical thixotropic gelling agents, including inorganic clays, are hectorite (solid under such names as Ben-a-Gel and Macaloid), montmorillonite (bentonite), synthetic hectorite (such as that sold under the name of Laponite), and combinations of these such as hectorite with montmorillonite (sold under the name of Veegum), and hectorite with a hydrocolloid such as hydroxyethylcellulose (sold under the name Bentone). Other examples of thixotropic gelling agents are the colloidal or fibrous aluminas such as sold under the trade names of Dispal, Alon and Baymal.

In addition to the gelling agent, the agent will contain a cleaner and preferably a nonionic cleaner is used such as the polyoxyethylene fatty acids esters and alcohol ethers sold under the trade names of Tweens, Spans, Myrij and Brij; oxyethylene oxypropylene polymers (Pluronics) and alkylaryl oxyethylene polymers (Triton). In addition, anionics such as sodium lauryl sulfate can be employed. The cleaning agent may be present in a concentration of from 0.01 to 20% and preferably 0.05 to 5%.

Since the composition of the present invention is not designed to be placed in the eye, ordinarily the lenses should be washed and preferably soaked and treated with a wetting solution before insertion in the eye. For this reason, the detergents used in the cleaning agent can be considerably more concentrated and fasteracting than cleaning agents which are used in solutions which might be placed on the lens directly before insertion in the eye.

The cleaning agent of the present invention is not intended for use in the eye, and, thus, it is not designed to be a sterile product. However, it is ordinarily preferred to include a preservative so that should the cleaning agent become contaminated, it would resterilize itself. For this purpose the organic mercury compounds such as thimerosol and phenylmercuric acetate, and other sterilizing agents such as methyl paraben, propyl paraben, phenylethyl alcohol and chlorobutanol are entirely suitable for this purpose. Concentrations of from 0.001 to 1.0 may be employed if it is desired to employ a preservative.

The following non-limiting examples illustrate the preferred embodiments of the invention:

-Continued Example 111 Polyoxyethylene fatty acid ester 1% Thimerosal 0.01% Purified Water q.s.

Example IV Laponite XLG 3% Sodium Sulfate 0.15% Sodium lauryl sulfate 0.1% Thimerosal 0.01% Purified Water q.s. 100% Example V Laponite CP 4% Calcium Chloride 0.04% Polyoxyethylene fatty alcohol ether 1% Chlorobutanol 0.5% Purified Water q.s. 100% Example VI Laponite CP 3% Aluminum chloride 0.045% Polyoxyethylene fatty acid ester 0.5% Methyl paraben 0.15% Purified Water q.s. 100% Example V11 Carbopol 940 0.5% Thimerosal 0.004% Polyoxyethylene alkylaryl ether 0.5% Sodium Hydroxide to'pH 8 Purified Water q.s.

(a) Carboxyvinyl polymer from B.F. Goodrich (1!) Sodium Ethylmercurithiosalicylatc (c) Polyoxethylene polyoxypropylene polyoxyethlene glycol from Wyandottc Chemicals (d) Synthetic montmorillonite All percentages are by weight.

We claim:

1. An aqueous thixotropic composition for cleaning hard contact lenses consisting essentially of:

from 0.1 to 20 weight percent of an anionic or nonionic detergent;

from 0.1 to 5 weight percent and in an amount sufficient to form a gel of a thixotropic gelling agent; from 0.001 to 1 weight percent of a sterilizing agent,

and water.

2. A composition according to claim 1, wherein said thickening agent is synthetic montmorillonite in an amount of from about 1 to 5 weight percent and said detergent is nonionic.

3. A composition according to claim 1, wherein said thickening agent is a high molecular weight carboxyvinyl polymer in an amount of from about 0.2 to 2 weight percent and said detergent is nonionic 4. A composition according to claim 3, wherein said sterilizing agent is thimerosal.

5. A composition according to claim 1, wherein said composition has a viscosity of 15,000 to 70,000 cps at 25C.

6. A composition according to claim 1, wherein said thickening agent is carboxyvinyl polymer in the amount of from about 0.5 weight percent, said detergent is polyoxyethylene alkylaryl ether in an amount from about 0.5 weight percent, said sterilizing agent is thimerosal, and the pH of said composition is about 8.

7. A method for cleaning hard contact lenses which comprises:

6 contacting a hard contact lens with a sufficient amount of an aqueous composition according to claim 6, to remove undesirable residue; and

rinsing said hard contact lens. 

1. AN AQUEOUS THIXOTROPIC COMPOSITION FOR CLEANING HARD CONTACT LENSES CONSISTING ESSENTIALLY OF: FROM 0.1 TO 20 WEIGHT PERCENT OF AN ANIONIC OR NONIONIC DETERGENT; FROM 0.1 TO 5 WEIGHT PERCENT AND IN AN AMOUNT SUFFICIENT TO FORM A GEL OF A THIXOTROPIC GELLING AGENT; FROM 0.001 TO 1 WEIGHT PERCENT OF A STERILIZING AGENT, AND WATER.
 2. A composition according to claim 1, wherein said thickening agent is synthetic montmorillonite in an amount of from about 1 to 5 weight percent and said detergent is nonionic.
 3. A composition according to claim 1, wherein said thickening agent is a high molecular weight carboxyvinyl polymer in an amount of from about 0.2 to 2 weight percent and said detergent is nonionic
 4. A composition according to claim 3, wherein said sterilizing agent is thimerosal.
 5. A composition according to claim 1, wherein said composition has a viscosity of 15,000 to 70,000 cps at 25*C.
 6. A composition according to claim 1, wherein said thickening agent is carboxyvinyl polymer in the amount of from about 0.5 weight percent, said detergent is polyoxyethylene alkylaryl ether in an amount from about 0.5 weight percent, said sterilizing agent is thimerosal, and the pH of said composition is about
 8. 7. A method for cleaning hard contact lenses which comprises: contacting a hard contact lens with a sufficient amount of an aqueous composition according to claim 1, to remove undesirable residue; and rinsing said hard contact lens.
 8. A method of cleaning hard contact lenses which comprises: contacting a hard contact lens with a sufficient amount of an aqueous composition according to claim 6, to remove undesirable residue; and rinsing said hard contact lens. 